In U.S. Pat. No. 3,218,107 of Harold L. Reinsma, which patent is owned by the assignee hereof, a seal and coupling assembly for a hinge joint is illustrated comprised of an inner sleeve member, an outer sleeve member and an intermediate elastic ring member securely maintained therebetween. One of the sleeves is press-fitted onto a track pin and the other of the sleeves is press-fitted into a track link with the seal being adapted to permit limited pivotal movement along the longitudinal axis of the pin.
In U.S. Pat. No. 2,338,169, George E. Dunn shows a universal ball joint having another form of seal for retaining lubricant within the bearing and preventing the entry of dirt and other foreign matter into the bearing assembly.
Another seal for use in a track for a tractor is illustrated in British Pat. No. 1,425,364 of the Kabushiki Kaisha Komatsu Seisakusho Japanese company. In that patent, a dust seal is illustrated having the shape of a W or a compound W so as to be capable of withstanding a thrust exerted on the bushing in the axial direction of the track pin.